Synthesis, crystal structure, hydrogen bonding interactions analysis of novel acyl thiourea derivative

Regulating intermolecular hydrogen bonding to construct solvation-induced emission shift quinoline derivatives for real-time monitoring of water content in organic solvents

Water constitutes the most prevalent impurity in organic solvents, exerting significant influence on chemical reactions and potentially leading to fires and explosions, even in minute quantities. Thus, the development of convenient, rapid, and cost effective fluorescent probes for real-time monitoring of water content in organic solvents is imperative. Although some fluorescent materials have been synthesized for this purpose, most suffer from laborious preparation processes and poor cycling performance, constraining their practical application. This study investigates the impact of hydrogen bonding on the aggregation-induced emission (AIE) properties of quinoline derivatives, leveraging quinoline as the foundational scaffold and its nitrogen atom as the hydrogen bond acceptor. Research findings elucidate that intermolecular hydrogen bonding of quinoline is the primary determinant of their AIE behaviors. By harnessing the phenomenon of water molecules forming intermolecular hydrogen bonds with quinoline nitrogen atoms, we devised a straightforward and rapid method to fabricate a fluorescent test paper for real-time monitoring of water content in organic solvents. Experimental results demonstrate that even minute changes in water content, down to concentrations as low as 0.5 % by volume in organic solvents, can induce fluorescence changes in the test paper, which also exhibits favorable cycling performance. This study not only explores the influence of hydrogen bonds on the AIE properties of quinoline derivatives but also pioneers the development of a cost-effective, rapid, and recyclable test paper for real-time monitoring of water content fluctuations in organic solvents.

Self-Assembled Nanodot Actuator with Changeable Fluorescence by π-π Stacking Force Based on a Four-Armed Foldable Phthalocyanine Molecule and Its Supersensitive Molecular Recognition

Designing intelligent molecules and smart nanomaterials as molecular machines is becoming increasingly important in the nanoscience fields. Herein, we report a nanodot actuator with changeable fluorescence by π-π stacking force based on a four-armed foldable phthalocyanine molecule. The assembled nanodot possessed a three-dimensional molecular space structure and multiple supramolecular interactions. The arms of the nanodot could fold and open intelligently in response to environmental molecular stimuli such as natural plant mimosa, which could lead to multiple variable fluorescence emissions. The nanodot was highly sensitive to the biomolecule thyroxine at the molecular level. The accurate molecular recognition and the changeable fluorescence conversion of the nanodot were attributed to multiple supramolecular interactions, including photoinduced electron transfer (PET), intramolecular fluorescence resonance energy transfer (FRET), and π-π stacking of the nanodots, resulting in an intelligent "nanodot machine with folding arms". The self-assembled nanodot actuators with changeable fluorescence have potential applications in advanced intelligent material fields.

Theoretical design and preparation research of molecularly imprinted polymers for steviol glycosides

In this paper, a novel molecularly imprinted polymer (MIP) for specific adsorption of steviol glycosides was designed, and the imprinting mechanism of self-assembly system between template and monomers was clearly explored. Firstly, steviol (STE) was chosen as dummy template, and the density functional theory (DFT) at B3LYP/6-31 + G (d, p) level was used to select monomers, imprinting molar ratios, solvents, and cross-linking agents. The selectivity to five steviol glycosides was also calculated. Importantly, reduced density gradient (RDG) theory combined with atom in molecules (AIM) and infrared spectrum (IR) was applied to investigate the bonding situation and the nature of noncovalent interaction in self-assembly system. The theoretical designed results showed that the template which interacts with acrylic acid (AA) has the minimum binding energy, and the complex with the molar ratio of 1 : 4 has the most stable structure. Toluene (TL) and ethylene glycol dimethacrylate (EGDMA) were chosen as the optimal solvent and cross-linking agent, respectively. Five hydrogen bonds formed in the self-assembly system are the key forces at the adsorption sites of MIPs through the RDG and AIM analyses. The MIPs were synthesized by theoretical predictions, and the results showed that the maximum adsorption capacity towards dulcoside A is 26.17 mg/g. This work provided a theoretical direction and experimental validation for deeper researches of the MIPs for steviol glycosides. In addition, the method of RDG theory coupled with AIM and IR also could be used to analyze other imprinting formation mechanisms systematically.